The joint venture of cell phone jammer will be open next month

VCO phase detector output signal is compared with the reference signal. In the frequency synthesis, in order to improve control accuracy, the phase detector working at low frequencies. The VCO output frequency is relatively high, in order to improve the control accuracy of the loop, you can not do without frequency technology. Phone frequency synthesis loop and more loop frequency synthesizer using a different divider different: the receiver first local oscillator (RXVCO, UHFVCO, RFVCO) signal with the channel change, and the frequency synthesizer in the loop divider is a programmable divider, the divider ratio is controlled by the data signal frequency synthesizer (SYNDAT \ SYNCLK, SYNSTR). The  china cell phone jammer company will establish a joint venture of  cell phone jammer.
Two oscillator VCO, also known as the IF VCO (1FVCO, VHFVCO), the signal is fixed, IF VCO frequency synthesis loop in the divider ratio is fixed. Divider output signal to the phase detector, and the reference clock signal for phase comparison. When the VCO is in normal working condition, VCO output a fixed frequency. If some external factors such as voltage, temperature can cause the VCO frequency is increased, the frequency output signal is f2 / N n higher than the reference signal, the phase detector to detect the changes, the output voltage decreases, the varactor both ends of the reverse bias decreases. This makes the varactor diode junction capacitance increases, changes in the oscillation circuit, VCO output frequency is reduced. If external factors cause the VCO frequency decreases, the control loop perform the opposite process. The joint venture of  cell phone jammer will be open next month.
The above is a description of how to make the VCO output frequency stability. But how to make the VCO frequency change it? In explaining this question, first to explain why the frequency of the VCO to change this problem. Because cell phones are cell phone, moving to another place, for the cell phone service cell (CELL) becomes another of the frequency, so they must change their cell phones to receive and transmit frequency. VCO frequency change is as follows: a new cell phone received a change in the frequency of signaling after the signaling demodulation, decoding, cell phones through three lines of the CPU (that is, the CPU SYNDAT, SYNCLK, SYNSTR feet) on the phase-locked loop issued instructions to change the frequency of the circuit, to change the programmable divider ratio, and in a very short period of time. In these three lines under the control of phase-locked loop output voltage to change, and with this has been larger or smaller to control the voltage of the VCO varactor diode, the VCO output frequency to change to the new area on the frequency of use. The joint venture of  cell phone jammer locates in the northern area.